Every season, a sizeable number of players vastly outperform preseason projections and expectations -- at least for a while. As the season progresses and fortune swiftly becomes misfortune, most of those players' stats level off to more expected levels. However, that isn't always necessarily the case, because certain players sometimes sustain their previously unexpected level of play and, in doing so, create a new, improved standard of performance. For the most part, it's possible to tell when a player's good play is based primarily on good fortune rather than merit. Normally (not always, of course), a player's peripheral numbers give a good indication of what his primary statistics should be in the future.
Alexis Rios is an interesting case. He was once a very highly-touted prospect whose major league output never quite matched his five-tool talent -- until this season, that is. In 31 spring training at-bats, he posted a line of .394/.645/1.039, but nevertheless began the season as the right-handed portion of a platoon with the left-handed Eric Hinske. In that time, he's absolutely crushed left-handed pitchers, as evidenced by his line of .432/.944/1.377 in 36 at-bats. Obviously, that earned him a good deal of playing time (thus abandoning the platoon to an extent) and he's responded by hitting .364/.574/.938 in 47 at-bats against right-handed pitchers. All in all, he's on pace for 40 home runs and approximately 140 runs batted in. Considering he had a mere 11 home runs in 977 major league plate appearances entering the season, that almost seems absurd. Now, to be fair, unexpected power surges of this sort have occurred in the past. In an even more extreme example than Rios', Hall of Fame outfielder Kirby Puckett hit four home runs in his first 1,327 major league plate appearances. In his next 680, however, he hit 31. And, much in the same vein as Alex Rios, his transition occurred during his third big league season. Of course, Puckett is a rare talent whose batting skills and baseball acumen allowed him to overcome an aversion to taking walks. Despite his increased success in most other facets of his game, Rios, in a similar fashion to Puckett, hasn't improved his patience at the plate one iota.
Consider his walk and strikeout totals during his first three seasons in the majors:
Year PA BB K BB:K
2004 460 31 81 0.34
2005 517 28 104 0.27
2006 92 3 14 0.21
Not only has his plate discipline not improved, but it's actually become appreciably worse. The following illustrates Rios' plate appearances arranged by the balls-to-strikes count during which his at-bat ended:
0-0 12 1-0 11 2-0 2 3-0 0
0-1 8 1-1 5 2-1 8 3-1 2
0-2 7 1-2 17 2-2 2 3-2 5
Plate appearances that ended with the count in his favour: 23
Plate appearances that ended with the count in the pitcher's favour: 31
Plate appearances that ended with a neutral count: 28
Certain figures were emphasized simply to make it easier to read (I hope it worked).
What's interesting is that not only has Rios only walked three times all season, but he's only been on the verge of walking (at least three balls) seven times. Based on this data, he's simply not swinging in very favourable counts. Vernon Wells, who isn't even a very proficient walker in his own right, has much more favourable totals:
Plate appearances that ended with the count in his favour: 44
Plate appearances that ended with the count in the pitcher's favour: 28
Plate appearances that ended with a neutral count: 50
Notice the contrast? Wells has managed to work to count to his favour, while Rios has failed to do so. The advantage of a favourable count is that the pitcher is much more limited in that scenario. Rather than having the luxury of throwing purpose pitches outside the strike zone in an attempt to get an easy out, he's almost forced to throw a strike for fear of falling further behind in the count. In the long run, Rios is more likely to see pitches that are much less hitter-friendly than the ones that will likely be thrown Wells' way.

AP PHOTO/CP, Frank Gunn
One area, on the other hand, in which Rios' performance has improved markedly is his ability to hit line drives and fly balls. Notice the difference between the types of batted balls that are predominantly being hit this year than in the past:
Year LD% GB% FB%
2004 20.5% 56.9% 22%
2005 19.5% 51.2% 31%
2006 25.7% 36.5% 43%
Please note that those FB% totals are not exact because I was forced to eyeball them from a graph. They should be rather close to their actual totals, however.
Moreover, it must be noted that his home runs as a percent of outfield flyballs (HR/F) has risen from 1.2% to 7.8% to 17.7% from '04-'06. That's a remarkable increase, to be sure.
What does it mean? Well, lower GB/FB (or higher FB/GB) ratios tend to yield more home runs and, naturally, a higher slugging percentage. In fact, Jeffrey Ackerman from Insider Baseball created charts that illustrate that trend. Using data from the past five season, he divided the data into ranges and found the average slugging and home run totals of players that fit into each range. Here's what he found:
GB/FB SLG HR
0.75 - below .517 29.5
0.76 - 1.00 .493 25.8
1.01 - 1.25 .472 22.1
1.26 - 1.50 .452 18.2
1.51 - 1.75 .421 12.2
1.76 - 2.00 .420 13.0
2.00 - above .394 7.8
Rios' current GB/FB ratio is approximately 0.80. That means he currently fits into the 0.76-1.00 range. As a result, if he can maintain his current performance (not necessarily a given), his totals would most likely reflect the ones listed in the table. That suggests that his current SLG of .735 is unsustainable over the course of an entire season. Assuming he finishes the season with a total of .493, as listed in the chart, his final line would decrease his OPS from 1.126 to .884, and that's without even taking a decrease in his OBP into account.
Through the first 27 games of the season, Rios has been very fortunate with respect to his batting average on balls in play (BABIP).
Year BABIP
2004 .355
2005 .314
2006 .413
BABIP is reliant upon a great deal of luck, of which Rios has apparently had plenty of this year. After last night, Rios ranked third in the majors in BABIP, behind Brad Hawpe and Casey Blake. He should regress, if only because it's highly improbable that anyone could maintain a BABIP that high. For instance, the highest total in the majors last season was .364 by Miguel Cabrera of the Marlins. All other things being equal, let's assume that Rios drops to even that lofty total to finish the season. In that scenario, his batting average would drop from .386 to .337. But remember, that's based on a very optimistic projection.
It appears as though Rios' surge in power may be a harbinger as opposed to an aberration. Last season he made a relatively large leap in that area, and it appears as though that will once again be the case in 2006. With that said, his 40 home run pace seems unattainable.
His plate discipline, on the other hand, is a legitimate concern. Since his batting average is set for at substantial drop, he should rely more on walks as means of getting on base. Walks rates are much more stable than batting averages, which tend to fluctuate much more often over time. Nevertheless, Rios should post personal bests this season, but they should differ from the level of performance he's attained thus far. In the end, a batting line close to .330/.500/.830 seems like a rather reasonable projection, if only a tad optimistic.